Unpredictability of Settlement of Shallow Foundation on Collapsible Soil

In the previous post we have discussed about the identification and mitigation methods for collapsible soil related problems. Shallow foundation on unsaturated collapsible soil can perform satisfactorily for sometimes. But these soil suffer sudden settlement of sufficient amount. This accidental settlement is induced due to sudden occurrence of water source which results flood through soil.

The volume decrease that occurs in collapsible soil under imposed load when wetted is dependent on following factors:

The difficulties in estimating settlement of collapsible soil include:

a. Variation of grading of soil

b. Variation of cementation of soil

These variations results variations in soils properties in both vertical and lateral directions. The most disturbing factors are these changing may occur within few centimeters and unpredictable occurrence of water source. The uncertainty arises as lateral and vertical extent of these variations cannot be predicted certainly.